1. Field of the Invention
The present invention is directed to a fiber-optic lighting system. In particular, the preferred embodiment of the present invention is intended to light the cabin interior of commercial passenger aircraft by transmitting light from a remote light source to individual light fixtures throughout the aircraft.
2. Description of the Related Art
Since people have been traveling by aircraft at night, there has been a need to light aircraft cabins to enable passengers to see. In the past, conventional incandescent and fluorescent lighting systems have been used to provide aircraft lighting. However, as will be explained below, these systems have numerous drawbacks.
The primary drawback associated with conventional lighting systems is that they require that many lamps be used throughout the aircraft. Each lamp increases the weight of the aircraft. Although increases in weight are undesirable in most apparatus, weight increases are especially undesirable in aircraft because every increase must be overcome by additional engine thrust in order to sustain flight. Added thrust requires more powerful and more expensive aircraft engines which also cost more to operate. Thus, weight increases the cost to the aircraft operator every time the aircraft leaves the ground.
Additional lamps also increase the electrical load on the aircraft electrical power distribution system. Because each lamp acts as an electrical resistance in the power distribution system and increases the load on the system, additional electrical power is required to light every additional lamp. Thus, the more lamps which are aboard the aircraft, the higher the potential electrical power requirement and the larger the power distribution system needed. Because larger power distribution systems cost more and weigh more, the addition of lamps further increases cost and weight.
Additional lamps also increase the maintenance costs associated with the lighting system because each lamp is a potential failure site which must be checked on a regular basis and replaced if necessary. Thus, as more lamps are used, the number of potential failure sites and the potential for the failure of at least one lamp increase. When a lamp fails, it must be replaced at an expense that includes not only the cost of the replacement lamp but also the cost of the labor associated with replacing the lamp. Therefore, as more lamps are used, the overall maintenance cost of the aircraft lighting system increases. Conversely, as fewer lamps are used, the overall maintenance cost decreases.
In addition, each lamp gives off heat. In particular, when incandescent lamps are used, the heat can be great enough to cause injury to persons coming in contact with the light fixtures and can even be great enough to cause a fire under some circumstances. The typical reading light fixture used in aircraft has a metal housing which is mounted in the valance or overhead luggage rack above the heads of seated passengers. The light fixture may be aimed by grasping the housing and swivelling it within its socket to direct the light toward a desired location. However, after a typical incandescent light is illuminated for a short time, the housing can become too hot to touch with bare hands without causing discomfort or even burns. In addition, this heat can become a fire hazard under certain circumstances. As more lamps are used, the potential for injury or fire increases. Thus, in order to minimize the potential of injury and fire, the number of lamps should be minimized and the lamps should be positioned away from passengers and flammable materials.
Many of the problems described above have been eliminated with the advent of fluorescent lighting systems in aircraft. Fluorescent lighting systems use less electrical power and generate less heat than incandescent systems. However, fluorescent lighting systems require ballast resistors, inverters and power units which create high voltage, high frequency, alternating electrical current. Because the fluorescent tubes are spaced throughout the cabin interior, the electrical current is distributed throughout the cabin interior by a power distribution network which can present an electrical hazard. Further, the power distribution network used for fluorescent lights generates high voltage electricity at a high frequency which is a potential source of both electro-magnetic and radio frequency interference. Because electro-magnetic and radio frequency energy can adversely affect aircraft communication, navigation and control systems, sources of electro-magnetic interference and radio frequency interference should be minimized aboard aircraft. In order to minimize these interferences, the size of the electrical power distribution network should be minimized.
Further, fluorescent systems use long, sealed tubes that are more fragile than incandescent lamps. As a result, fluorescent lamps are more easily broken during routine maintenance than incandescent lamps. When lamps are broken, maintenance and housekeeping costs increase. In addition, because the tubes are made of glass, there is a potential for injury associated with broken lamps.